Against my better judgement, I thought I would try contacting Sarah. 

It was a short call. She mostly talked at me.

I tried explaining who I was. She just said that she was aware of who he was now and had enough to deal with with BM2, so she wasn't about to deal with "some other woman" and whatever "sob story" she (I) "wanted to pull". I did verify where he worked and she just said "not for long".

I did learn that she had filled for a paternity test on the "cousin's" child and that she had guardianship in her own right due to how it was set up, but nothing else.